![eva emerson](https://i0.wp.com/www.sciencenews.org/wp-content/uploads/2014/11/EE_thumbnail.jpg?resize=116%2C150&ssl=1)
Cells use time’s rhythms to organize different functions. Precision timing of neurons and muscles, directed by the brain, controls the body’s movements. Time is a tool that brings order to our lives. It is ironic, then, to discover that physicists explain time as a product of disorder: Its forward direction reflects the unalterable tendency to increasing messiness in the universe.